Flexible plastics hoses

ABSTRACT

A method of manufacturing a flexible plastics hose the method comprising extruding a strip of a first plastics material and a reinforcing element of a second plastics material, winding said strip into a helix around a driven mandrel and bonding adjacent turns together by pressure applied between the mandrel and roller means external thereof to form a tubular wall of said plastics material and simultaneously winding said reinforcing element around the helix of said first plastics material in spaced apart helical turns and pressing it into the first plastics material by said roller means so as to partially embed said reinforcing element into said tubular wall.

United States Patent 1191 Stent et al.

FLEXIBLE PLASTICS HOSES Vernon Dennis Stent; Derek Cecil Wright, both of Woking, England inventors:

[30] Foreign Application Priority Data Nov. 27, 1972 United Kingdom 54636/72 [52] US. Cl. 156/143; 156/195; 156/244; 156/425 Int. Cl. 331C 3/00 Field of Search 156/143, 244, 195, 425, 156/428,429,443,446,190;138/122,l44, 150, 155, 172, 174; 29/477, 477.3, 477.7

[56] References Cited UNITED STATES PATENTS 11/1955 Beare et al 156/143 1/1956 Wauburton 156/143 UX June 17, 1975 2.731.070 1/1956 Meissner .1 [56/143 3,658,625 4/1972 lshikawa an ms/195x Primary ExaminerCharles E. Van Horn Assistant Examiner-David A. Simmons Attorney, Agent, or Firm-Larson, Taylor & Hinds [5 7] ABSTRACT A method of manufacturing a flexible plastics hose the method comprising extruding a strip of a first plastics material and a reinforcing element of a second plastics material, winding said strip into a helix around a driven mandrel and bonding adjacent turns together by pressure applied between the mandrel and roller means external thereof to form a tubular wall of said plastics material and simultaneously winding said reinforcing element around the helix of said first plastics material in spaced apart helical turns and pressing it into the first plastics material by said roller means so as to partially embed said reinforcing element into said tubular wall.

5 Claims, 7 Drawing Figures 1 FLEXIBLE PLASTICS I-IOSES This invention relates to a flexible plastics hose of which the tube wall comprises a helically-wound strip of plastics material the turns of which are bonded together and surrounded by spaced turns of a helicallywound reinforcing element which is at least partially embedded in the material of the tube wall (hereinafter called a flexible plastics hose of the kind referred to"), and more particularly to a method of manufactur ing a flexible plastics hose of the kind referred to.

From one aspect the invention consists in a method of manufacturing a reinforced plastics hose of the kind referred to, comprising extruding a strip of a first plastics material, simultaneously extruding a reinforcing element of a plastics material which (a) is more rigid and/or has a higher mechanical strength than said first plastics material and/or (b) has a core of a material which imparts to said reinforcing element more rigidity and/or a higher mechanical strength than said first plastics material, winding said strip into a helix around a driven mandrel while the plastics material is still in a plastic condition and bonding adjacent turns together by pressure applied between said mandrel and roller means external thereof to form a tubular wall of said plastics material. and simultaneously winding said reinforcing element around said helix of said first plastics material in spaced helical turns having the same pitch angle as said helix of first plastics material while guiding the reinforcing element into said spaced helical turns and pressing it into the first plastics material by said roller means so as to partially embed said reinforcing element into said tubular wall and to feed the tubular wall with the reinforcing element partially embedded therein axially of the mandrel.

By selecting for the hose wall and the reinforcing element plastics materials which are compatible, the helical reinforcing element may be fused or bonded to the tubular wall of the hose by the pressure exerted by the roller means.

The reinforcing element is preferably wound so as to overlie the joins between adjacent turns of the strip of the first plastics material.

The reinforcing element may be made by extruding plastics material around a core, such as a metal wire or a textile cord to provide the reinforcement or additional reinforcement.

The guiding of the reinforcing element into its spaced helical turns is conveniently effected by annular guide grooves in the roller means. spaced apart corresponding to the pitch of said turns, and of a depth such that the base of a groove presses the reinforcing element to the desired partial extent into the wall layer of the first plastics material. The groove side walls act like a nut on the turns of the partially projecting reinforcing element moving therethrough to advance the formed hose towards and off the end of the mandrel. A plurality of roller means may be disposed around the mandrel which, in order to minimise frictional resistance against the advance of the formed hose along the mandrel, preferably comprises a plurality of driven rollers disposed on a circle around the centre axis of the mandrel, thereby providing gaps between the peripheral zones of the mandrel rollers against which the inner surface of the formed hose is supported.

The roller guide grooves need only extend along the mandrel for a distance such that the engaged turns of progressively hardening plastics materials exert a total reaction sufficient to ensure the forward feeding of the formed hose. Thereafter, if desired. the reinforcing element can be pressed further in to the plastics material of the tube wall, or a further extruded strip of plastics material may be wound around the formed hose, and preferably bonded thereto by pressure, so that the reinforcing element becomes completely embedded in the wall of the finished hose.

The invention also consists in reinforced flexible plastics hoses made by the said method or apparatus.

In order that the invention may be more readily understood, reference will now be made to the accompanying drawings, in which:

FIG. 1 is a perspective view of one embodiment of an apparatus according to the invention.

FIG. 2 is a plan view of part of the apparatus of FIG. 1, and

FIGS. 3 to 7 are fragmentary sectional views of various different embodiments of hose according to the invention.

Referring to FIGS. 1 and 2, the apparatus comprises a mandrel 1 around which are helically wound plastics extrudates from two extrusion devices 2 and 3 arranged alongside the mandrel. Each extrusion device comprises an extrusion die head 2a or 311 to which plastics material is fed from extruders 2b or 3b respectively. A strip 8 of a first thermo-plastics material. such as a soft grade of polyvinylchloride, is extruded by the device 2 and fed to the mandrel l and at an angle to the centre axis of the mandrel corresponding to the pitch angle at which the strip 8 has to be wound around the mandrel along a helical path so that adjacent turns of the helically wound strip 8 will touch one another or substantially so. A second plastics material is extruded by the device 3 to form a reinforcing element 9, the second plastics material, for example, rigid polyvinylchloride, being more rigid and/or having a higher mechanical strength than the first plastics material. The extruded reinforcing element 9 is fed to the mandrel l at the same pitch angle as the strip 8. As shown in FIG. 1 the extrusion nozzle of the device 3 is arranged above the extrusion nozzle of the device 2 so that the element 9 will be wound on the mandrel over the strip 8.

The mandrel l is mounted horizontally on a support 4 and comprises a plurality of mandrel rollers Ia which are circumferentially equi-spaced on a circle around and extend parallel to the centre axis of the mandrel. The mandrel rollers la are driven at the same speed and in the same direction, as indicated by the arrows, from the belt driven pulley 5 through a suitable arrangement of gears, not shown.

A plurality of guiding and pressing roller assemblies 6, four in the embodiment shown, are disposed at circumferentially spaced positions, preferably circumferentially equi-spaced positions, around the mandrel for guiding the reinforcing element 9 and the strip 8 so that they will be wound around the mandrel at the desired helical pitch angle and for pressing the plastics materials thereof against the mandrel to bond the turns of the strip 8 together and to partially embed the reinforcing element 9 into the plastics material of the strip 8. Each roller assembly comprises a plurality of roller-sections 6a, 6b etc. which are rotatable, each section indepen dently of the others, on a common shaft II. The shaft 11 of each assembly is carried from the support 4 by an adjustable bracket 12 which enables not only the radial spacing and circumferential location of the associated shaft 11 to be adjusted relative to the centre axis of the mandrel l by the bolts [21: securing the bracket 12 to the support 4, but also the inclination of the axis of the shaft 11 relative to the central axis of the mandrel. tangentially of the mandrel. to be adjusted by turning the part of the bracket to which the shaft ll is attached about a bolt 12b which can be tightened to lock the two parts of the bracket together in the adjusted position. Each rolier assembly is disposed opposite a mandrel roller la and adjusted so that the axis of its shaft 11 intersects a radial line from the centre axis ofthe mandrel through the axis of the said opposing mandrel roller and is inclined to the centre axis of the mandrel at an angle equal to the pitch angle ofthe helical turns of the reinforcing element of the hose to be made.

Each roller section 6a, 6b, 60 etc. has a portion formed with a guiding groove 7a, 7b, 7c etc. for receiving the reinforcing element, adjacent guiding grooves of a roller assembly being spaced apart by a distance corresponding to the pitch ofthe helical turns of the rcinforeing element. Since the shaft ll is inclined to the axis of the mandrel, its spacing from the surface of the opposing mandrel roller la increases in the direction of hose formation. and to compensate for this and enable the successive guiding grooves to maintain guiding contact with successive turns of the reinforcing element, the grooved portions of the successive roller sections ofa roller assembly increase in diameter in the direction of hose formation. Preferably also the diameters of the troughs of the guiding grooves, and also the portions of the roller sections between adjacent grooves, similarly increase in diameter in the direction of hose formation to maintain pressure contact on the reinforcing element 9 and the material of the strip 8 throughout the length of each roller assembly. Theoretically. uniform contact pressure requires the increment of the diameters to follow a curved line depending on the inclination of the roller assembly and the diameter of the opposing mandrel roller la but in practice it has been found satisfactory if the diameters increase in a frusto'conical or simple taper form as illustrated in FIG. 2.

Successive roller assemblies in the direction of winding of the plastics materials are so positioned axially of the mandrel that the guide grooves thereof locate with the turns of the reinforcing element of the hose being made. Thus, in the case of the embodiment illustrated in FIGS. 1 and 2, having four roller assemblies equally spaced around the mandrel, the guiding grooves of corresponding roller sections of successive roller assemblies in the direction ofwinding are displaced axially of the mandrel by a distance equal to one quarter of the pitch of the turns of the reinforcing element.

As shown, the first roller section 6a of each roller assembly has a buttress portion 13 of such diameter that it touches or substantially touches the surface of the opposing mandrel roller. These buttress portions 13 serve to guide the first turn of the strip 8 into the desired helical path, the pressure exerted by them on the side of the strip 8 urging it towards the previously wound turn and assisting in feeding the formed hose along the mandrel, In the embodiment shown, the surface ofeach buttress portion 13 which engages with the side of the strip 8 is of frusto-conical shape to substarn tially correspond with the slope of the side surface of the strip 8 which it engages, it being preferred that the strip 8 be formed with a rhombic cross-section, as shown in FIG. 3, as this formation assists in the bonding of adjacent turns of the strip 8 by the applied radial pressure.

As the extruded strip 8 and the extruded reinforcing element 9 are in the thermoplastic condition as they are wound around the mandrel, the roller sections of the roller assemblies 6 press them together to partially embed the reinforcing element into the tube wall formed by the strip 8 and also to bond adjacent turns of the strip 8 together Conveniently, the guiding grooves are arranged to guide the reinforcing element 9 so that it overlies the join between adjacent turns of the strip 8 as shown in FIG. 3. This has the advantage that the pressure exerted by the guiding grooves to partially embed the reinforcing element in the material of the strip 8 ensures adequate pressure between adjacent turns of the strip 8 to achieve a good bond. The portions of the roller sections between the grooves apply such pressure on the portions of the strip 8 between the turns of the reinforcing element as is necessary to obtain a good bond between its turns. Preferably, the plastics materials of the strip 8 and reinforcing element are compatible so that as they are wound and pressed together in the thermoplastic condition, they will also be bonded together.

As the plastics materials are wound around the mandrel, the guiding grooves act as a kind of nut on the partially projecting helical turns of the reinforcing element, assisted by the force exerted by the portions 13 of the roller sections 6a on the side of the first turn of the strip 8, to advance the hose along the mandrel as it is formed, and finally off the end of the mandrel. The finished hose H discharged from the end of the mandrel, after plugging its open end, may be floated, while still rotating, on water contained in a long trough, whereby the plastics materials are also water cooled.

The reinforcing element, instead of or in addition to being made of a plastics material which is more rigid and/or of greater mechanical strength than the plastics material of the strip 8, may be provided with a core of metal wire, a textile or nylon cord, or of other material which provides the desired reinforcement. The core may be incorporated by providing the extrusion device 3 with a cross'head die 3a through which the core 10 is introduced as shown in FlG. l. A core of metal wire, such as bare stranded wire or other conducting material when earthed, also serve to avoid a build up of static electricity along the hose and can also be used as an earthing wire between end couplings of lengths of hose for discharging static electricity which may be generated at a hose nozzle.

An earthing wire may alternatively be provided as an insert in the strip 8, and may be introduced therein by providing the extrusion device 2 with a cross-head extrusion head.

If desired, the strip 8 can comprise two or more lay ers of plastics materials, for achieving any particular desired hose characteristics. For example, it may have an inner layer of a plastics material possessing advantageous properties, eg. oil resistance, for the use to which the hose is to be put. For example, the inner layer, which forms the inner wall of the hose, may be of polyurethane. The outer layer may be PVC.

Axial sections through the walls of examples of hose produced according to the invention are illustrated in FIGS. 3 to 7. Each hose comprises a tube wall constituted by the helically wound strip 8 of the first plastics material the turns of which are bonded together, having the helically wound reinforcing element 9 around the outside thereof and at least partially embedded therein, the adjacent turns of of the reinforcing element 9 being axially spaced apart. The reinforcing element which possesses greater rigidity or a higher mechanical strength than the wall material of the hose which it surrounds, serves to reinforce the hose. Preferably. as shown, the reinforcing element 9 overlies the joins between adjacent turns of the strip 8 constituting the tube wall. In the embodiments illustrated in H65. 3 and S the reinforcing element has a circular cross-section and in that illustrated in FIG. 4 it has a wider, flatter crosssection. In FIG. 6 the element 9 has an eccentrically disposed core in the form of bare strand wire sur rounded by the second plastics material. In the hose of FIG. 7, two reinforcing helices are wound around the softer plastics material, one of the reinforcing helices 9a being an extruded filament of the more rigid or harder plastics material and the other 9b comprising a strand wire covered with a conducting PVC (e.g. a PVC containing conductive particles). Where two different reinforcing elements are wound around the tube wall an extra extrusion nozzle is provided for the additional reinforcing element and the form of the guiding and pressing rollers must be appropriately modified.

While particular embodiments have been described, it will be understood that various modifications may be made without departing from the scope of the invention. Thus the guiding grooves 7a, 7b etc. may progressively decrease in depth, so that the reinforcing helix becomes progressively further embedded in the tube wall material as the hose formation proceeds. The free ends of the roller assemblies may carry plain roller sections for achieving further embedment or flattening of the reinforcing element.

However, it must be borne in mind that the advance of the hose along the mandrel is produced by the total reaction of the turns of the projecting portions of the reinforcing element (the plastics material of which, as does the plastics material of the strip 8, progressively cools and hardens somewhat as it advances along the mandrel, which cooling can be assisted by impinging cold air thereon) on the guiding grooves, assisted by the axial forces exerted by the buttress portions 13 on the strip 8, so that care must be taken to provide sufficient axial reaction to advance the hose being made without undesirable distortion. For making hoses of particularly long length, or of softer materials, it may be necessary to provide two or more sets of roller assemblies, arranged in tandem along the mandrel, in order to provide sufficient axial reaction to advance the hose along the mandrel. in this regard, the construction of the mandrel of a plurality of mandrel rollers with spaces therebetween where the tube wall is unsupported, is important in reducing the resistance to axial advance along the mandrel.

According to another modification, the first roller section 6a, or at least the buttress portion thereof. of each roller assembly may be positively driven. The

drives may be effected through suitable gearing from the pulley 5, and in order to enable the inclination of the shafts 11 to be adjusted to suit the hose to he made, they may be connected to the driving means by universal joints.

Further, instead of forming the guiding grooves at the ends of a roller section as shown in the illustrated embodiment they may be provided at an intermediate position along a roller section.

We claim:

1. A method of manufacturing a flexible plastics hose of the kind referred to, said method comprising extruding a strip of a first plastics material. simultaneously extruding a reinforcing element ofa second plastics mate rial, winding said strip into a helix around a driven mandrel while the plastics material is still in a plastic condition and bonding adjacent turns together by pressure applied between said mandrel and a plurality of annu larly grooved roller means circumferentially spaced around and longitudinally along said mandrel and with the annular grooves therein disposed in a helical path corresponding to the pitch angle of said helix to form a tubular wall of said plastics material, and simulta neously winding said reinforcing element while the plastics material thereof is still in a plastic condition around said helix of said first plastics material in spaced helical turns having the same pitch angle as said helix of first plastics material by passing the reinforcing element through the annular grooves of said plurality of roller means to guide the reinforcing element into said spaced helical turns and to press it into the first plastics material by said roller means so as to partially embed said reinforcing element into said tubular wall, the plurality of grooved roller means acting like a nut on the partially embedded reinforcing element moving therethrough and engaging the progressively hardening helical turns of the reinforcing element for such a distance along the mandrel as to ensure a total reaction sufficient to advance the tubular wall with the reinforcing element partially embedded therein axially of the mandrel.

2. A method as claimed in claim 1, wherein the plastics materials of the reinforcing element and the strip are compatible and the reinforcing element is bonded in the tubular wall of the hose by the applied pressure.

3. A method as claimed in claim 1, which further includes introducing a core of metal wire into the reinforcing element as it is extruded.

4. A method as claimed in claim 1, including urging the turns of the strip along the mandrel by buttress means against which the side wall of the first turn of the strip engages as it is wound on the mandrel.

5. A method as claimed in claim 1 which further consists in extruding the strip with a rhombic cross-section and winding the strip so that the side walls of the strip overlap as the strip is wound on the mandrel, and in guiding the helically wound turns of said reinforcing element to overlie the joins between the adjacent turns of said strip. 

1. A method of manufacturing a flexible plastics hose of the kind referred to, said method comprising extruding a strip of a first plastics material, simultaneously extruding a reinforcing element of a second plastics material, winding said strip into a helix around a driven mandrel while the plastics material is still in a plastic condition and bonding adjacent turns together by pressure applied between said mandrel and a plurality of annularly grooved roller means circumferentially spaced around and longitudinally along said mandrel and with the annular grooves therein disposed in a helical path corresponding to the pitch angle of said helix to form a tubular wall of said plastics material, and simultaneously winding said reinforcing element while the plastics material thereof is still in a plastic condition around said helix of said first plastics material in spaced helical turns having the same pitch angle as said helix of first plastics material by passing the reinforcing element through the annular grooves of said plurality of roller means to guide the reinforcing element into said spaced helical turns and to press it into the first plastics material by said roller means so as to partially embed said reinforcing element into said tubular wall, the plurality of grooved roller means acting like a nut on the partially embedded reinforcing element moving therethrough and engaging the progressively hardening helical turns of the reinforcing element for such a distance along the mandrel as to ensure a total reaction sufficient to advance the tubular wall with the reinforcing element partially embedded therein axially of the mandrel.
 2. A method as claimed in claim 1, wherein the plastics materials of the reinforcing element and the strip are compatible and the reinforcing element is bonded in the tubular wall of the hose by the applied pressure.
 3. A method as claimed in claim 1, which further includes introducing a core of metal wire into the reinforcing element as it is extruded.
 4. A method as claimed in claim 1, including urging the turns of the strip along the mandrel by buttress means against which the side wall of the first turn of the strip engages as it is wound on the mandrel.
 5. A method as claimed in claim 1 which further consists in extruding the strip with a rhombic cross-section and winding the strip so that the side walls of the strip overlap as the strip is wound on the mandrel, and in guiding the helically wound turns of said reinforcing element to overlie the joins between the adjacent turns of said strip. 